I Need Help Selecting A Better Wheel

I sharpen paper & string cutting knives ans use the two wheels shown below. The knives range in size from 1/2" x 1-1/2"x 3/16" to a little longer.

I need to cut in .001" passes and keep having to resurface the wheels often.
I used to have a white rock that held up better,
We use an old Do ALL grinder.

Can you recommend? View attachment 126836 View attachment 126837