Normally, if the pump is leaking you would only need to replace the actual pump portion of the pump/motor combination. Just as in the case of a car whose transmission fails, you replace only the transmission and not the whole engine/transmission assembly. But... in your case with the manufacturer not operating in Thailand any longer, you may have no choice other than to replace the whole pump. With that said, Hayward makes a very good pump.
When I needed to replace a pump, I ordered the same brand and model because I thought it would be a simple swap out with no plumbing modifications required. I was wrong though, as the inlet and outlet locations changed slightly in the newer version. In any event, you will most likely have to modify some of the plumbing when installing a new unit. Make sure you get new union fittings for connecting to the new pump, as you probably won't be able to re-use the existing ones.
Pumps are usually mounted on a concrete slab or pad. You may want to consider pouring a small slab. You'll definitely need to modify the inlet and outlet pipes to accommodate a different pump location, but try to avoid adding sharp angles if possible.