Mr. Welland’s sensitive domesticity shrank from the discomforts of the slovenly southern hotel, and at immense expense, and in face of almost insuperable difficulties, Mrs. Welland was obliged, year after year, to improvise an establishment partly made up of discontented New York servants and partly drawn from the local African supply.
There are no more uses of "insuperable" in the book.
Show samples from other sources
This objection would be insuperable if Homer had been an Ithakan.
Homer -- The Odyssey
I came to the conclusion that difficulties, well-nigh insuperable, lay between me and the safe possession of the beautiful little vessel.