Ah, those aren’t (generally called) inserts, those are rivnuts.(rivet+nut)
I’d start with trying to put pressure on the flange below the screw head, see if I can get enough purchase to undo the screw that way.
Next attempt would probably be to dribble some cyanoacrylate around the flange, hope it’d hold for removing the screw.
Next would be to drill or grind off the screw head, then grind the flange off to remove the whole rivnut before installing a new one.