If you mean that part of the actual door has been routed out to form a handle it is an integrated handle. Although I suspect you mean an actual attached 'handle' that is the width of the door.
If you are really keen to replace them you could visit a hardware store. Look for aluminium mouldings. There are many different shapes to choose from. Just get enough [they usually come in 8' lengths] so that they can be cut to lengths enough for all the doors. Many aluminium extrusions have different functions and so have no holes in them for screws. Drill a few small holes just big enough to put the screw through. If the screws are countersunk [angled on the bottom part of the head] you can lightly drill in each hole with a 1/2" drill just enough so that the hole is countersunk - that way the screws will sit flat when afixed.
As a last resort you can also visit a carpet store for mouldings, but note that most carpet strips have 'teeths' on them to grab the carpet.
Have fun.