do i need to re attach the ceramic ring to the impeller.     and what do i need  to use

I went through a lot of water pump leaking on a D6 with the same basic Cat 318 engine as your grader. I don't remember all details any more. But I did glue the ceramic ring back on one impeller. I had the water pump out 3 or 4 times in a 2 week period. Turns out the problem was leaking pre combustion chambers in the head pressuring the water and the overflow pipe would not handle all the pressure and water would leak by the water pump seal. I believe the glue impeller was used for a short time.