In a SharePoint Designer situation, insert actual Web Part in the targeted Web Part zone after exporting it from any page.
This works best only if you plan to use it on a single Site Collection, as repeated deployments must be manually performed elsewhere. In such situations an automated deployment is recommended, and in such cases the best way to have a web part automatically provisioned for you is to use the AllUsersWebPart (in this case RootWebOnly ensures that your Page Layout is only deployed on the Top-Level site as it should be!).
One additional tip: Repeated deployments (via features) of the Page Layout - if already in use - must be performed by temporarily changing the Page Layout, updating it, and re-applying to all Pages (make sure the Content Type has the same structure across Page layouts to avoid using data)!
The example below could be used in an automated deployment via Features with a Module.
<Module Name="PageLayouts" RootWebOnly="True">
<File Path="PageLayout\Home.aspx" Url="Home.aspx" IgnoreIfAlreadyExists="true">
<AllUsersWebPart WebPartZoneID="Left" WebPartOrder="1">
See also example detailed here