Yes sir that is the washer mine had! I think it is more than just a spacer, as it conforms to the contour of the inside of the pulley, and without it, I suspect, the sharp edge of the waterpump flange would rest somewhere along the radius of the pulley, and concentrate force on the edge. However, I imagine sheer age and metal fatgue could have resulted in that carnage, especially if, as you said, the belt was too tight.
