I did this once to some locomotive wheels quite successfully. Access to a lathe is necessary to make everything concentric. Drill out the wheel centers about 50 thousandths or more oversize; it is not critical. Make a cast iron or brass plug to be a tight press fit into the hole, about a half thousandth bigger than the hole in the wheel. Press in the plug, and drill out the plug to the correct size for the axle. The hole needs to be the size of the smooth part of the axle, and not the bigger spline dimension. Replace the axles if necessary to get good sharp splines to cut into the wheel bushing. While you have the wheels and axles out, check the axle bearings in the frame for excessive wear and replace them if necessary before pressing on the wheels. Access to a wheel press to press on the wheels straight is a must. You only get one chance to do this right, or you start all over again.
The second option is to buy new wheels...
Larry