I'd bin the stub axle anyway, the surface is damaged so a new bearing won't seat properly and might itslef seize on. If you have to get the old one off then just bust it up with a cold chesel, wear eye goggles though as the bits are very sharp.
I was told that if you electric weld to a bearing race the hardened metal will crystalise and become brittle, but I just prefer LR special tool#1, BFH :)