I have 3 and none of them have ever bent. They appear to be some kind of very flexible steel and when they do flex, they spring right back.I had one and wasn't impressed with it at all. The first time I put a tight patch through the bore the rod bent on me. Not to mention the coating had started flaking off everywhere.
I have managed to damage the coating on one of my Dewey rods, but I know how and when I did it, and frankly, I'm not surprised at the damage to the coating given what I did to the rod.
I bought mine some years ago. Perhaps they have changed since then.