In my Batch Box rocket firebox I've used board similar to this stuff (it's widely available in Europe)
Vermiculite board
In my experience it works well but does abrade after a while even when loading fuel carefully. I've also used it in several woodstoves as firebox lining and baffles and it does wear after prolonged exposure to high heat. It really needs to be treated as a consumable part.
Incidentally, My BB firebox uses the insulating board for the walls and ceiling and I use firebrick splits for the floor (backed up with superwool insulation). The splits cope fairly well with the logs being loaded into the firebox - they survive longer in that application than the insulating board.