Poor Quality Parts

Installed a brand new engine purchased from VW Barons. Unfortunately they don't keep the distributor and were out of stock of a water pump. Purchased the water pump and electronic distributor from Goldwagon Durban. After 4 months of use , engine doing 4000 km, the distributor key way broke off and stopped turning the oil pump. Switched off the engine immediately. Upon observation it could be seen that the metal quality at the area of the key-way was weak and inferior that broke off and stopped turning the oil pump shaft. Installed the old bosch distributor that had done over 600 000km on the old engine and the car is back to normal runs well. A week later the water pump started to leak.