What's in a Name? הושע becomes יהושע

(1) "And Moses called to Hoshea etc." - [Moses] prayed to G-d about [Hoshea] that [he] should be saved from the counsel of the spies.

(1) And Moses called Hoshea son of Nun Joshua: This does not mean that the people from then on called this man Joshua. It means that the man who had been referred to as Hosheah son of Nun in his father’s house was the one whom Moses now referred to as Joshua. The change had occurred already at the time when Moses appointed this man to be his personal valet. It was customary to change the names of people who were promoted in rank. We find this the first time when Pharaoh changed Joseph’s name to Tzofnat Paneach (Genesis 41,45) We find it again in Daniel 1,6 when Nevuchadnezzar’s chief officer changed Daniel’s name to Belteshazzar. This had been a reference to a Babylonian idol so named. The first time Joshua’s name had been changed was in Exodus 24,13.

Moses said to Joshua: Apparently Moses called him Joshua from the day when he first began to serve him; evidently "Moses changed the name of Hoshea son of Nun to Joshua" (Numbers 13:16) is telling us that the Hosea selected to be among the spies is the one whose name Moses had changed. The Midrash says Moses changed his name to make it a prayer, "May God preserve you from the counsels of the spies," which tells us that Moses knew about the incident in advance. Or perhaps at that time Moses made the name change public so that from that time on everyone would call him Joshua instead of Hoshea.