Mine looked the same and did not wear the impeller. Changed the impeller out this spring after 2 seasons and the impeller still looked new. Never had any pressure issues running this pump. In fact, my pressure picked up over stock at idle. And yes, that inner wear plate would be easy to miss. And on my pump was a bear to get the old one out to replace with the rebuild kit.

They did give him something for the pain... the wear plate that he forgot to install. lol

Glad it was an easy fix.

Thin coat of white lithium is all I have ever used to pre-lube any impeller in any housing. I believe the Hardin rebuild kit also suggests using lithium grease.

you threw it away

I've been running this pump on my 525 for years with no problem. Used to change impeller every year but it always looks like new so now I do it every 2 years.

water base KY or glycerin to install impellers, Johnson pumps has done many studies on this and have found glycerin to be the best for installing impellers. Glycerin -- It washes out at start up very very quickly - many other products do not wash out very quickly. And dish soap exacts the oil out of impellers. All rubber products are a form of an oil base .

Johnson includes the glycerin in every impeller kit they sell for a reason. Like I said they tested everything

Actually tech speaking clean water is the best for impellers no matter how you slice it because thats what they live in 24 / 7

Impellers and the housing is all about tolerances - when wrong it does not work nor flow correctly