Well, you can only try.
Losing most of a tree's feeder roots while being roughly transplanted midsummer is going to be hard to recover from, but, you never know I guess.
The nectarine may have more of a chance than the cherry, if the cherry is larger -- if either of them are more than 4-5' tall (and very slim and poorly branched) I would not give them good odds.
Any chance you could rig something like a pavilion of shadecloth, to keep the worst of the sun off the tree for the next couple months? THe less direct sun it gets, the less evapotranspiration, meaning the less water loss, meaning the less that the remaining roots are being counted on to do.
Oh, one thing that I've done that's SEEMED helpful when transplanting trees with inadvertantly partly bare roots -- get some hormone rooting powder (Rootone, or that sort of thing) and dust *just a very little bit* on the exposed roots. You can shake a little onto a paper towel and then pat the exposed roots with it. You are not making shake-and-bake, you just want a little bit of it on the roots. It has seemed to me that woody plants I've done that to, when being moved roughly, have done better than ones where I haven't. Obvioulsy this is not an option if the nectarine's been planted already but you could try it for the cherry.
Good luck, have fun,
Pat
