I have a nylon part that goes between the motor shaft and the impeller. I can not find it in the part diagrams and have been told that it is part of the motor by the parts salesperson. I just can’t believe that such a flimsy piece would not be replacable.
What was the original complaint?
Could the part you’re describing be a damaged part of the housing, shaft or other component that may be damaged due to the prevoius problem ?
I don’t see any nylon /plastic insert between the impeller and motor shaft on any of my parts information or component break downs either, I would have to presume there is housing damage or internal damage and it has attached to the shaft.
I don’t recall anything like you’re describing when I was in the field and repairing units.
Anything else would be a guess. You may want to consider the motor pump assembly as a repalcement part.