Leviticus 18:20 LITV
(20) And you shall not give your semen to your neighbor's wife by lying with her, for uncleanness with her.
Leviticus 18:20 KJV
(20) Moreover thou shalt not lie carnally with thy neighbour's wife, to defile thyself with her.
I have cross-referenced Leviticus 18:20 with the Interlinear Scripture Analyzer and it reads "to woman of companion of you not you shall give emission of you to seed to be unclean of in her" .
Based, on the word for word rendering of the Hebrew of Leviticus 18:20, the KJV's rendering of Leviticus 18:20 is not even close to the spirit of the verse. We understand that in the days of Moses there might not have been a technique for artificial insemination and that to become a surrogate father for the sterile companion the sperm donor would have to have sex with the woman of the sterile man. However, God does not approve of any kind of deal involving the wife of somebody else. It seems that God would have also disapproved artificial insemination.
[Some permissible sexual relationships before Moses did not make it to the Exodus. For example, the Jews came from the union of a half-brother and a half-sister (Genesis 20). God banned that kind of union at the Exodus.]
Genesis 20:11 (NIV)
[11] Abraham replied, “I said to myself, ‘There is surely no fear of God in this place, and they will kill me because of my wife.'