Oil Sump in Pump?
Many of the older pumps, (all that I have worked on) have self-contained oil sump. Maybe a diesel mechanic will provide a more definitive answer. The newer, common rail system don't seem to have their own sump but operate off of engine oil - at least my Ford/International DIT does. I tried to post a picture of the type but only wound up with a lot of garbled link info. The type I am talking about is bolted to the side of the block and usually has to be rotated against the block to set timing. The oil level has to be checked and oil does need to be changed.