I'm extremely dubious... on the heavy and medium duty trucks (International, Freightliner, etc.), if you've worn a groove into the axle, you can buy over-sized seals and hardened sleeves that slide over the seal surface. Those are usually good for +100K miles but they're in 55-65 HRC range. I'm doubtfull that J.B Weld has either the hardness or wear characteristics to last very long. Additionally I'm doubtful of the ability to get a really clean mating surface. Any eccentricity in the finish or porousness would massively accelerate seal wear.
On the other hand... I'm continually amazed at how effective modern polymers are and would have nothing but respect for you should you attempt this experiment and report out.