Actually, the sha are based very loosely on a concept from feng shui (Chinese geomancy).
In feng shui, sha is a negative form of chi that flows through leylines in the ground and can cause negative emotions, misfortune, and even illness. It moves in rigid, straight lines and is attracted to manmade structures.
Blizzard confirmed this during their art panel at Blizzcon 2011.
"The sha was influenced by their studies about feng shui, so they ended up going with it. The sha could possess pandas, they could become bosses--it grew as they researched."
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http://www.wowhead.com/news=196626/b...-wow-art-panel
Visually, I think the sha are simply based on the concept of yin and yang. Just about anything sha-touched, including the sha themselves, are covered in swirls of white and black.
Although the mantis has some Chinese symbolism, there really isn't very much. The mantid are moreso an extension of the existing aqir mythology in Warcraft. The mantid are related to the qiraji and nerubians and similarily worship an Old God.