There’s a good Q&A over at High Rankings about changing URLs for SEO. Jill Whalen, one of my favorite SEO experts, suggested no. In other words, does www.yourcompany.com/red-leather-dog-collar.html do better than www.yourcompany.com/item123.html?
She said, and I agree,
"It is a common misconception that keywords in URLs are somehow helpful to search engine rankings, when in reality, they have very little (if any) effect on rankings."
Search engine algorithms change all the time, often in response to what search engine marketers are doing to game the system. So, there’s no way of knowing what the algorithms will be like down the road.
My recommendation is to keep your current URLs as they are; you may have build up some good incoming links and trust at the search engines for that page. However, you may want to hedge your bets going forward, and create more keyword-rich URLs.
One word of caution: don’t over do it. Search engines tend to frown on pages that seem "over-optimized." Be clear with out being pushy.