Yeah, that was a bitch on a friend's '98 Ram, too.  It's pressed in with an
O-ring.  I'd try a pipe wrench on it, try and get it to turn inside the pump
(to break loose the corrosion that's holding it in place).  It's too late
now, but there are aftermarket pumps available with a threaded hold for a
threaded hose nipple, which eliminates both the problem of re-using the old
tube, and the very good possibility of a leak when re-installing it.

If the old pump is out, and it's trash anyway, you could try splitting the
neck, where the tube presses in, with a Dremel.  Be careful not to cut too
deep that you damage the tube.

At worst case, a new bypass tube is $10 from NAPA (part# 6601692).  Don't
drive yourself crazy...

Put it in the freezer overnight, then hit it with heat...the housing
side that is.