Check the fuel line connections first
If your engine runs well and you have no diesel fuel showing up in your crankcase oil, the fuel pump bladder is intact. You may want to check the actual location of that leak again. Typically one side of the low pressure fuel pump is a rubber fuel line with hose clamp to the fuel pump and the line running to the engine fuel filter is a metal fuel line with copper washers. Either of those connections could be loose and leak, and the copper washer should be replaced if you remove that or any other fuel line connection utilizing copper washers. You should replace the rubber fuel line and the copper washers if you do change out the fuel pump. Also make sure to insert the new fuel pump into the engine block with it's actuating arm on the cam, not alongside it, as something will bend or break when you tighten the mounting bolts or turnover the engine if the parts are not aligned properly.