There are many moving parts inside that pump that have to leak. No rubber seals, just metal to metal. All the fuel that leaks fills that housing and eventually comes out the the return fuel fitting. If it runs - and your 100% sure the fuel isn't leaking into the engine-oil sump past the driveshaft seals - it has to fill up pretty quick.
Are you sure you didn't mess up those driveshaft seals and all the excess diesel isn't going into your crankcase? Check your dipstick.