Why not just run the aluminum body directly on the steel shaft?

1. Anywhere whatsoever basically totals the rocker, unless you have the facilities to board the hole oversized (without altering its location), and then put a bushing in. for something made with a replaceable bushing, you press the old one out, press the new one in, ream or hone to size. Your component is now far more easily kept serviceable, with just an arbor press and a drill press.

2. Aluminum is not a really great bearing material against Steel. If there is ever a problem with it running dry, it's fairly prone to galling. Brass and bronze have much better inherent lubricity, and are more forgiving of occasional insufficient lube.