I came across this error when deploying my application along with the embedded python distribution. I had added pip to the embedded distribution, a Lib/site-packages folder and installed a number of packages to the embedded distribution.

With the help of the answer from @tbrugere, I used DUMPBIN with the /DEPENDENTS option on cv2.pyd and found the only dependency not in the SyWOW64 directory was python3.dll. The target machine was a newly created VM without python installed.

Copying python3.dll from the embedded distribution's top level folder to the Lib/site-packages/cv2 folder did the trick.