I have never heard of a pen raised pheasant going broody. If one did it would be a one in a million chance that she would stay on the nest long enough to hatch the eggs and probably no chance that she would raise the chicks. If you choose not to use an incubator, bantam hens espically Cochns are excellent. As far as feed goes, all game birds pheasants, quail and partridge require a high protein level of feed (at least 23% protein and 28% even better) Stay away from the meat and fish, but the other things you mentioned are good as TREATS, not for a regular diet. Stick with Game Bird or Turkey Feed. They also love non salted peanuts. be sure they are shelled and non-salted. Salt will kill your birds. And best of all watermelon.
It is can be done and is awesome to experience. Too many people take the eggs away which discourages the birds to go broody. Too many people keep their pheasants in pens that are barren & with no natural cover for the birds to feel comfortable enough to go broody. Over the years, I have allowed the following species to hatch and rear their own (make sure that the mesh at the bottom of the aviary is either solid or small enough to prevent the chicks from escaping): Silver, Edwards, Swinhoe, Kalij (Horsfield's & Lineated races), Golden, Amherst, Elliot's, as well as Erckel's, Black, & Grey Francolin (also Gambel's Quail, Vulturine Guineafowl). It can be done and encouraged. Of these species, the males (except the Elliot's) played a major part in helping the hen rear the young. They would protect the young, even brood the young - offer food and nothing is more satisfying than watching a wild species simulate a wild behavior in captivity. If I had a hen that refused to sit, I would use another species or one of her own kind to hatch them. Before I was unable to keep pheasants, there were several years I didn't even waste the electricity on turning on an incubator. (some of the pheasants I used to own are now on exhibit at the Sunset Zoo in Manhattan, KS, so anyone out in that area, be sure to tell them I miss them very much, but happy they are still fulfilling their purpose of education!!!!)
To encourage the behavior, read as much as you can on the natural history of the species and try your best to simulate that when building and landscaping an aviary. If you visit the pheasant section section on gbwf, I have several photos of pheasants of a variety of species rearing their own. In my opinion, I feel that the parent reared birds are healthier, happier, and when the time comes (should it ever) that re-introduction is possible, there will be captive birds that have not had the instinct "bred" out of them just for the sake to produce more birds to sell.
Dan Cowell