The oil pump is the heart of your engine as it is used to force pressurised oil to various essential moving parts. The Giulia oil pump is a complete aluminium casting with a detachable pickup/strainer which house a pair of gears. In general pump life is excellent providing the engine is looked after with regular oil and filter changes but many older classic Alfas are bordering on forty years old and, as one would expect, oil pumps are showing signs of general tiredness and wear. Since 2001 genuine oil pumps have been in short supply since Alfa Romeo ran out of stock, and as so often happens, various makers of non-original pumps took this as a sign of diminishing demand---hence the crippling shortage that has forced owners to resort to re-fitting the old pump or having to look for a decent secondhand unit. The fitting of an old or secondhand pump is decidedly risky because failure would inevitably wreck the engine.
GOOD NEWS! The good news is Alfa Romeo is again making pumps in very small numbers, just enough to satisfy immediate demand. As the exercise is apparently to use up existing components by assembling them into new pumps this situation is unlikely to be long term. If you are thinking of undertaking a major overhaul in the near future it would be worth buying a pump for stock---also consider pistons and liners which are apparently due for a major price increase next year due to higher manufacturing costs linked to short production runs due to diminishing demand!