I don't know how cost-effective it would be, but it's probably possible to machine an axle shaft down and press a sleeve over the bearing area, then use a tool post grinder to bring it back down to standard size. I'd use air hardening tool steel material for the sleeve and heat-shrink it into place- - - - -when it cooled down the Brinell hardness number would probably be pretty close to right.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!