Here's a task for you: design a bearing that can operate deep in saltwater/on the ocean floor under heavy load with little to no maintenance for a very long time. Durability is more important than precision.

I have the correct answer in the first comment. Compare your design to the established one and see if it's any different! Share your design in comments!

The answer is convex plate covered with synthetic disc diamonds sliding in the concave plate covered with the same kind of disc diamonds. Because literally everything on the ocean floor is softer than Mohs 10, the bearing will just grind everything that comes inside it and remain spotless. Also, no lubrication required for diamond-on-diamond action.

Remember: Mohs scale works. Your phone's screen gets scratched by your keys inside your pocket because of how abundant quartz is. It's literally on every surface. It's harder than gorilla glass. It's in your pockets, embedded in the fabric of your pants.

But diamond doesn't care about quartz.

If you thoroughly clean everything, you can spend all day trying to scratch gorilla glass with your keys, to no avail.

It's so weird hearing box cutter blade engaging sapphire and leaving a mark, just to later realize that it's not the blade that was scratching sapphire, it's sapphire and microquartz that were grinding away at the blade like a huge but very fine file. And the mark left was metal, so it wipes off without a trace.