Torch method is probably way faster, but my visible pump had its original glass cylinder in place.
Simply took vise grips and attached near rod end(blind hole) and clamped tightly on rod.
Worked the vise grips back and forth using hand power.

At first, zero movement or play, but slowly as the rust got crushed from back and forth pressure rod moved freely.
Slow and steady won the race for me. Did not break off any rod ends in the blind rusty holes.
Your mileage may vary..