CHurCH = It begins and ends with the same basic sound.
CHeriSH + The "CH" is like that in CHURCH. The "SH", however, is the sound in show, shoe, sure, sheep, ship, etc.
I should add that the "ur" sound in church and the "er" sound in cherish are different.
church = hurt, burn, fern, her
cherish = air, hair, bare, bear, care