First, they are not "plastic" wear rings, they are made of a very hard material, almost like a super hard nylon (would be my best description) I'd much rather have the impeller up against nylon than brass if things did get out of sinc. Personally would rather buy a wearring than an impeller.
Ken F
Well after talking with Duane these wear rings are well not nylon or plasic. I am willing to try one, But I am sending Duane my impeller to be fit to the wear ring. This will be very interesting to see results.