Those inserts are for the 11 bolt water pumps and go inbetween the divider plate and the timing cover where it feeds the block. There should be a second plate on the 8 bolt pumps that goes in between the water pump and the divider plate that has the chamfers.My guess is it helps divert the coolant and helps to pump more effectively. I just did a 8 bolt pump a few weeks ago with the after market stainless steel divider plates. They do need some trimming and grinding to fit them in the timing cover properly.
