Gray or Black?
What color is the rubber you found? The OEM water pump seal is battleship-gray, and it's the shaft that wears grooves into it which allows the coolant/oil exchange past the seal lips- the lips take a beating & wear so it needs replaced at the same time to maintain a tight seal
If the bits are black more likely cam chain guides...
950 Adv 'S'
'87 KLR650 - <200K miles
"Like the Energizer Bunny, just keeps going & going..."