OOTB there is no such webpart. However, there are lot of plugins available on the Internet which you can use and integrate with on SP pages.
Couple of plugins you can use -
1) html share buttons - this one is simple & easy to integrate. Just add the necessary buttons that you want in a script editor webpart or page layout etc. This however wont provide info about how many were shared.
2) Addthis - requires registration. Once registered tt provides you with a unique code. This also provides info regarding how many pages were shared on FB, twitter etc.
3) AddtoAny - similar to Addthis requires registration. You can select what all social media services you want to share on.
4) Sharethis - requires registration. Similar to addthis. Provides a tracking code. You can also implement it like in this SO question ShareThis Button to Open in Popup
5) Pure html share buttons
Add social sharing buttons to your site
Disclaimer - I am not affiliated to any of the above mentioned products in any way.
There are many other plugins also available. You can choose whichever fits your requirement.
Bottomline - To implement them, you will most likely need to add their either provided script in a Script editor webpart or inside a page layout or if you want it across the site, then add it inside your masterpage.