Macbook pro (Mid 2012 ) replaced with a 500GB SSD drive. 2.5 GHz Intel Core i5 processor. 8 GB memory.
Yes it will run great. More RAM is always better, 8GB RAM is adequate.
How to upgrade to macOS Catalina - Apple Support
always advised to have a back up plan in place, before upgrading. Only in this way can you fall back if things go side ways.
Verify you are prepared for no 32 bit apps.
With the release of macOS 10.15 Catalina, applications will have to be 64-bit. App developers will issue updated apps if they want their apps to work on this newest macOS upgrade
32-bit app compatibility with macOS High Sierra 10.13 ... - Apple Support
https://support.apple.com/en-us/HT208436
Check Your Apps and Prepare for a 64-bit World
https://www.stclairsoft.com/Go64/index.html
Locate all 32-bit apps in System Info
http://osxdaily.com/2018/03/06/find-32-bit-apps-mac/