It would also be possible to fabricate a sleeve to slip over the worn area and weld into place, then machine it back to the correct diameter. The worn area would need to be machined a bit smaller, make the sleeve slightly oversize, split it, and then weld it over the shaft. There would be less welding involved than building up the entire worn spot, with less chance of distortion, or changing the strength of the shaft. Lots of ways to skin this cat, but there needs to be some "outside the box" thinking that most shops won't consider.
Jerry
